[Myplaceoryours]

The short answer to your question is - No. Whisking the whites separately will not help. Any air you whisk in to the egg whites would not last 36 hours. Speaking of 36 hours, I believe one element of your problem is that you need to make your batter in smaller batches and prepare it more than once in 36 hours. 36 hours is a long time for a batter to rest and, I suspect, whomever uses the batter throughout those 36 hours stirs it each time it's used. That stirring overdevelops the batter, increasing the development of the gluten in the all purpose flour; hence, chewy pancakes.
I don't understand why you have water in the recipe, except to reduce the fat content. Also, the manner in which a pancake is turned greatly affects the way they cook. Pancakes that are turned gently turn out MUCH better than pancakes that are lifted and dropped onto the grill.
Hope that helps.
One last point. I don't see any butter or oil in your recipe. I'd include melted butter if I were making the batter. I might also try mixing half all purpose flour and half whole wheat flour.
Good luck...................
I forgot to mention - room temperature batter (which I doubt you're using if you're allowing it to stand for as long as 36 hours) will produce a better pancake than batter that comes straight out of the refrigerator. The cold batter cools the grill down pretty dramatically. The eggs in the batter, regardless of the other ingredients, don't even begin to cook until 144 - 149 degrees.